This invention relates to heating apparatus, particularly of the type which makes use of heat from existing heating or cooking apparatus.
Open fires, closed fires, boilers, cookers (solid fuel, oil or gas), ceiling mounted radiant gas heaters and etc, loose valuable heat to the outside atmosphere without the benefit of all the heat generated having contributed to the inside atmosphere of the home or workplace.
Heat is transmitted by three means; Radiation, Convection and Conduction. Most of the heat transmitted to the room from an open fire is by radiation. No convected heat emits from an open fire--it cannot. All the convected heat and most of the conducted heat--which conducted heat in turn transfers to convected heat in the main as air passing over the fire surrounds draws on that heat and takes it away up the flue--is lost up the flue and in turn to the outside atmosphere.
All fires--unless supplied with air for combustion in a sealed ducted source from the exterior--actually lower room temperature for some time after starting up. An open fire on an exterior wall is at best 10% efficient, on an interior wall is at best 20% efficient. A free standing closed solid fuel fire is at best 30% efficient. Solid fuel, oil or gas cookers are at best 53% efficient. Ceiling mounted radiant gas heaters are at the 30% efficient, and wall mounted radiant/convector gas heaters are at best 50% efficient. Solid fuel, oil or gas boilers are in the 50%-60% efficiency range with the most efficient being a very low output gas boiler in the region of 74% efficiency. These figures take into account all the heat generated which actually finds its way first to the interior including that which bleeds through the linings and structure of the flue to the interior. The remaining percentage is the heat energy which is lost to the outside atmosphere without benefit to the purpose for the heating system--this is the heat lost up the flue in the form of the convected heat generated in the system, and in turn a part of that convected heat which is converted to conducted heat and lost through the exterior lining and structure of the flue.